Instead of deriving the Ward-identities in a specific bulk theory, in this paper we take them as postulates. For our purpose, it is useful to think of a theory as a collection of \(S\) –matrix elements – the natural observables in a holographic description of asymptotically flat space-time. The global symmetries act on this collection. Since we are talking about \(S\) –matrix elements, it is convenient to introduce physical asymptotic states. These asymptotic states determine the operator-content of the theory. In the best possible situation both the operator content and the \(S\) –matrix elements will be determined to a large extent by the symmetries themselves. For example, the infinite dimensional asymptotic \(U(1)\)  symmetry [1]}, [2]}, [3]}, [4]}, [5]}, [6]} is found in theories which have massless spin–1 particle or photon. So if we do not have the (soft) photon operator in the theory then the theory cannot have the \(U(1)\)  symmetry. Therefore, it is not too unreasonable to expect that in a holographic – dual description the infinite dimensional global \(U(1)\)  symmetry will predict the existence of (soft) photons.
